Pulled the mower out of it's cozy hiding place (as you do when HAVING to mow the lawns) Check & filled oil & fuel, even cleaned the air filter ;-) Got my air muff's (can't hear the kids complaining about the noise) Started it up & got on with the mowing .
ONE catcher load later & on to the 2nd catcher the mower turned it's self off. Hhhmmmm I thought? & !
The motor took about 15 turns to stop rotating? HUH
toyboy3,
Mar 23, 10:09am
Run out of compression ?
jmma,
Mar 23, 10:15am
Piston broke, typical Kiwi (o:
skull,
Mar 23, 10:21am
It sounds like a lack of compression, what does it feel like when you pull the starter cord? Valve stuck open? Plug out & thumb over the hole and pull the cable, if you want to kill 2 birds with one stone hold the metal end of the spark plug wire at the same time.
mrfxit,
Mar 23, 10:28am
LOL yep all 3 sort of correct answers.
Conrod let go Not even a whimper, just simply let go & slowly spun down to a stop. Might have been a single tap noise but HEY, I had my air muff's on.
sr2,
Mar 23, 10:42am
LOL, a similar thing happened to me last summer. The old B&S 4 stroke stuck a leg out of bed (through the crankcase) and a big chunk of bottom end hit my gumboot with enough force to make one hell of a bruise on my ankle. I had to employ some descriptive adjectives, (and a few beers) to recover from that one!
quickbuck,
Mar 23, 11:02am
Mine did that when Master 12 decided that he could mow the lawns faster if he mucked with the Governor. Ended up with a half mown lawn with an oil stain where the B&S died.
mrfxit,
Mar 23, 11:08am
LOL guys, good events worth remembering aye. Never had a brigg's do this before, Seen a few but never mine.
Had a blade center bolt shear off, left the blade half buried in the ground under the mower & the motor running freely.
Ran over an oil filter buried in the long grass which banana'd the crank on a freshly rebuilt motor.
Hire center I worked at many years ago had an iron horse motor mower come back with a shattered block split on all sides & (of course) the customer swore it simply stopped on her, (it did, but thats not the point)
gmphil,
Mar 23, 11:23am
sein a lot of lawn mower broken never had one break on me ! oh hang on ive never mowed a lawn lol slight fib did once when I was young looked novel so i had a go in decided there in then not for me !
nzmax,
Mar 23, 12:26pm
Only ever had one mower die on me about 6yrs ago, which was replaced with an ancient 70's Gold coloured Masport with a B&S motor that was rescued from the dump by my neighbour for parts. It didn't have an air filter, used more oil than petrol. to the point that sometimes smoke from the exhaust was like thick fog, and it knocked like you wouldn't believe, yet it started on the first pull everytime as long as you cleaned the spark plug first. That thing just wouldn't die. After 2 seasons I finally bought a new mower, more so because the smoke issue was getting a bit embarrassing.
mrfxit,
Mar 23, 12:32pm
In my defence, I didn't do the rebuild on this motor.
The last motor I rebuilt was doing lawn contracting for approx 1 year & then 6 years of 3 domestic lawns only. It died because the top crank bearing got so badly worn that I couldn't adjust the coil gap anymore
kazbanz,
Mar 23, 2:38pm
conrod bolts come loose?
jmma,
Mar 23, 3:04pm
Mowing on a slope?
mrfxit,
Mar 23, 3:17pm
Nope. Bolts are intact & still done up Will have a photo shortly
Looking at the colour of the oil it was too thick for splash lubrication ,big end bearing would of seized and snapped con rod then crankshaft beat it to death not that unusual.
mrfxit,
Mar 23, 8:28pm
Crank journal looks pretty good & clean, might just throw another piston & rod assemble back on it. It's still a good block but I do have another engine available that I am considering as a quicker idea
aj.2.,
Mar 23, 8:37pm
Yep, just change the motor, you may spend a lot of time on rebuilding that busted motor, only for it to fail again. I would think the crank is well out of round, and will be a fail point. Edit Also what is the bore like , and is it the same size as the piston that you have? Still think go with other motor.
mechnificent,
Mar 24, 6:22am
If the rod hasn't seized to the crank, which should be easy to tell, and which I doubt because the rod is not bent sideways like they get when the bearing/crank has seized. then I'd throw another piston and rod in it if I had the spare. just for a try. It's only an hour or twos work. And those things are simple. you can file the cap of the replacement rod if there is too much bearing clearance. and they will run for years.
mrfxit,
Mar 24, 7:25am
Yep the block is fine so will probably park it for another day.
Freaky stuff now. The other spare motor (complete later model mower chassis & motor) has been sitting beside the shed in the open air for about 7 years. Tipped some petrol down it's throat & it fired ok, so put some in the tank & some more down the carb & it's running fine now. Haven't touched a dang thing on it but did of course check the oil level & even thats clean.
I don't have the matching handle or catcher for that model but I DO have a far better condition Masport body (+ bag catcher & handle) then my current 1 so will do some swapping around today.
yz490,
Mar 24, 10:30am
Been there & done that when [abusing] my old briggs trying to mow an overgrown lawn, i bent the throttle thingy around to crank the revs up so wasn't surprised. Love the old briggs though, simple & [generaly] totaly reliable.
yz490,
Mar 24, 10:46am
Meant to add [this'll have ya head scratching]. Rele too close for comfort has a big Husqvarna Ride-on with a 13 horse v twin briggs & broke a conrod on the RH cylinder about a year ago [i'm mean't to be fixing it but can't get inspired]. Still runs [& vibrates till past about half throttle]. Piston is sitting right at the top & suppose if it's not sucking there's no fuel to explode & blow it back down. Couldn't believe it at first but must be broken at the bottom & the bottom bit still on the crank. Initially pushed it down & crank hit it of course so turned crank other way which moved it then started it up & suppose crank case pressure blew it up to the top again [horizontal motor] & there it stays. [should i push post message! ] too late.
mechnificent,
Mar 24, 12:43pm
HA. see I said they were tough. Mrfixit and YZ490
My son has a yz490, bored to 510. and he's also got a water cooled head motor oot of some motard thing.
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